Web thinning machine

ABSTRACT

Web thinning apparatus includes a yoke mounted grinding wheel and motor movable by a lead screw into engagement with the tip of a drill mounted in a clamp and orbited in an elliptical path by an adjustable orbit drive mechanism.

United States Patent 1191 1111 3,813,822 1 June 4, 1974 Grob [5 WEB THINNING MACHINE 2.601172 8/1952 Ruolle 51/219 R 3. 7,122 10 9 2 H c l 2 [76] Inventor: More T 1549 U130 3,324,146 12/1925 51:1 :02: Grafton, 53024 3.621.613 11/1971 Groh er al 1. 51/90 [22] Filed: May 8, 1972 Primary Exummer-Al Lawrence Smith [2]] Appl' N03 251,356 Assistant EraminerNicholas P. Godici I Attorney, Agent, or Firm-Edmond T. Patnaude [52] US. Cl. 51/90, 51/96, 51/219 R 511 [1111. c1. B24b 3/32 1 1 ABSTRACT [58] Field of Search 51/985, 96, 219, 288, Web thinning apparatus includes a yoke mounted 51/90, 94 R, 94 C, 33 R grinding wheel and motor movable by a lead screw into engagement with the tip of a drill mounted in a [56] References Cited clamp and orbited in an elliptical path by an adjust- UNITED STATES PATENTS able orbit drive mechanism. 2,583,159 1/1952 Swanson 51/219 R 9 Claims, 10 Drawing Figures PATENFEB BN 4 m SHKUJUQ FIG. 4

PMENIEDJUH 4 m4 SHEET t [If 4 FIG. 6

FIG. 7

FIG. 8

WEB THINNING MACHINE The present invention relates in general to the art of thinning the webs of twist drills, and it relates more particularly to a new and improved web thinning machine of the type in which the point of a drill and a rotating grinding wheel move in a relative orbital path to remove material from the web of the drill.

BACKGROUND OF THE INVENTION When sharpening twist drills, it has long been the practice to thin the point end of the webin a metal removal operation by engaging the end portion of the web with the abrasive edge of a rotating grinding wheel. Grooves are thus formed in the sides of the web at the point of the drill to provide a chisel edge whose length is less than the thickness of the web of the drill. U.S. Pat. No. 3,62l,6l3 discloses a method and apparatus wherein a rotating grinding wheel and a drill are moved with respect to one another in an orbital motion such that the grinding wheel contacts the web and is swept thereacross for a brief period only during each orbit thereby resulting in a cooler grinding operation, longer grinding wheel life and a more facile set-up and operation than had heretofore been achieved using the teachings of the prior art. The present invention constitutes an improvement of this patented system.

OBJECTS OF THE INVENTION An object of the present invention is to provide a new and improved web thinning apparatus which operates in accordance with the basicprinciples disclosed in U.S. Pat. No. 3,621,613, but which is less expensive to manufacture, easier to operate, and which provides greater control over the size and shape of the grooves formed in the web of the drill being sharpened.

Another object of the present invention is to provide a new and improved clamping mechanism suitable for holding a drill in a web thinning machine.

A further object of the present invention is to provide a new and improved mechanism for moving the end of a workpiece in a controlled, adjustable, elliptical orbit.

SUMMARY OF THE INVENTION Briefly, the above and further objects may be realized in accordance with the present invention by providing a web thinning machine having a drill support and clamp assembly mounted intermediate its ends for universal movement, an orbital drive mechanism connected to the drill support, and a grinding wheel and associated drive motor mounted adjacent to the drill support and movable by means of a lead screw into engagement with the web of a drill. The clamp assembly is of the scissor type and positions the point end of the drill in substantially the same position relative to the grinding wheel for a wide range of drill sizes. The orbital drive causes the point end of the drill to travel an elliptical orbit and includes means for adjusting the size of the orbit thereby to control the shape of the groove ground in the web. The clamp assembly also permits axial and rotational adjustment of the drill relative to the grinding wheel further to control the length and position of the groove ground in the web.

BRIEF DESCRIPTION OF THE DRAWINGS Further objects and advantages and a better understanding of the invention may be had from the following detailed description taken in connection with the accompanying drawings, wherein:

FIGJI is a front elevational view, partly in cross section, of a web thinning machine embodying the present invention;

FIG. 2 is a perspective view, partly broken away, taken from the left side of the machine as shown in FIG. 1;

FIG. 3 is an enlarged, end view of the drill bit clamping mechanism of the present invention;

FIG. 4 is a sectional view taken along the line 44 of FIG. 3;

FIG. 5 is a sectional view taken along the line 55 of FIG. 3;

FIG. 6 is a side view of the orbit adjustment connector of the present invention;

FIG. 7 is an end view of the connector of FIG. 6 taken from the left as viewed in FIG. 6;

FIG. 8 is an enlarged view of the grinding wheel position locking assembly of the present invention;

FIG. 9 is an end view of a drill being thinned and showing the orbital path of the drill during such operation; and

FIG. 10 is a view of the drill position.

DETAILED DESCRIPTION OF THE DRAWINGS Referring now to the drawings and particularly to FIG. 1 thereof, there is shown a machine 10 for use in thinning the webs of twist drills. This machine includes a base 11 on which is mounted a motor driven, thin grinding wheel 12, a drill support and clamping assembly 13, and an adjustable orbiting mechanism 14 for causing the point end of a drill I5 mounted by the assembly 13 to travel in an elliptical orbit relative to the grinding wheel 12. The plane of the grinding wheel 12 is positioned at an adjustable angle relative to the axis of the drill 15 in substantial alignment with the uppermost flute, and while the drill I5 is being driven in an orbital path, the grinding wheel 12 is slowly moved downwardly in its own plane by an operator using the handwheel 16 thereby to grind in the end portion of the web of the drill a groove having a cross-sectional shape corresponding to a segment of the orbital path of the drill. Such a groove is shown at 17 in FIG. 9. After a groove 17 of the desired depth has thus been ground in the top side of the web, the wheel 12 is elevated away from the drill, the grinding motor is swung out of the way for clearance, the drill is rotated through and the operation is repeated to grind a similar groove in the opposite side of the web. It will be understood by those skilled in the art that although the operation of the machine 10 is described herein is connection with adouble-fluted twist drill, the machine 10 may be used for thinning the webs of various other types of drills.

As best shown in FIGS. 1 and 2, a hollow stand 20 is mounted on the base 11 and the drill support and clamping assembly 13 is in turn mounted thereon. The

assembly 13 includes a sleeve 21 universally pivotable in a fixed support sleeve 23. The sleeve 21 is provided with a bore 24 for fixedly receiving a rigid tube 25. A second tube 26'is telescopically received in the righthand end of the tube 25 and held in place by means of a thumbscrew 27 threadedly received in a hole in the tube 25.

In order to resiliently bias the drill 15 disposed in the tubes 25 and 26 toward the left into engagement with a clamp assembly 28 carried by the tube 25, a coil spring 29 is mounted in the tube 26 between a fixedly mounted stop 30 and a-generally cylindrical drill engaging tail stock member 31 slidably mounted in the tube 26. A rod 32 extends through the spring 29 and is secured in the member 31 to hold the spring 29 in place. The right-hand end of the rod slidably extends through the stop 30 and is threaded at its distal end to receive a nut 33 which limits the leftward movement of the member 31. The rear end 15a of the drill 15 is adapted to be received in a conical recess 35 in the face of the member 31 to position the rear end of the drill on the axis of the tube 25.

The clamp assembly 28 is best shown in FIGS. 3 and 4 and includes a generally tubular supporting frame 38 having front and rear walls 38a and 38b in which a horizontally disposed lead screw 41 is journaled. The screw 41 is provided with oppositely threaded portions 42 and 43 on which a pair of clamping nuts 44 and 45 are respectively mounted so that as the screw 41 is rotated by means of a wheel 46 the nuts 44 and 45 are moved toward or away from one another depending upon the direction of rotation of the wheel 46. Except for the di rection of the thread therein the nuts 44 and 45 are identical. As shown in FIG. 5 the nut 44 includes upstanding and depending pin portions 47 and 48. These pins on the nuts 44 and 45 are slidably received in slots 49 and 50 in bifurcated end portions of a pair of clamping members 53 and 54 pivotably supported on a pair of posts 55 and 56 fixedly mounted in parallel relationship between the top and bottom walls of the frame 38.

The clamp member 53 has an angularly extending arm 57 and the clamp member 54 has an angularly extending arm 58 provided with a large opening 59 through which the arm 57 extends. A vertical post 60 is mounted near the end of the arm 58 and is provided with an annular flange 61 near the top which is adapted to engage the upper edge of a flute of the drill 15 near the point end thereof. Similarly, a post 63 extends upwardly from the arm 57 and is provided with a notched upper surface 64 as shown in FIG. 3 to engage the lower edge ofa flute of the drill 15. The heights of the posts 60 and 63 are selected so that when the point end of the drill 15 is clamped therebetween, the drill 15 is aligned with the axis of the tube 26. It may thus be seen that as the wheel 46 is turned to move the clamp posts toward one another into engagement with the forward end ofa drill positioned in the tube 26. The clamp posts travel in an arcuate path so that the point of any diameter drill within the range of the machine is at substantially the same location for grinding relative to the grinding wheel 12 without any further axial adjustment ofthe drill. Moreover, the upper drill engaging portions of the clamp posts 60 and 63 automatically locate the web of the drill in the proper position for grinding.

The clamp assembly 28 can be rotated and also moved axially on tube 25 by opening clamp screw 39 with clamping lever 40. This permits a wide variation of web thinning configurations. Two graduated scales, 66 and 67 one for circular, the other for axial motion, make it possible to exactly repeat desired results. The scale 67 is mounted to frame 38-and provides a reference line for the scale 66. The scale 66 is disposed on a ring mounted on the tube 25 and provides a reference line for the scale 66.

The orbiting assembly 14 comprises a stand 70 mounted on the right-hand side of the base ll and having an upper wall 71 which is slanted from the horizontal at an angle of about 20. A speed reducing gear box 72 driven by an electric motor 73 is mounted on the stand and has an output shaft 74 lying at an angle of 20 from the horizontal.

An orbit adjuster 75 is mounted to the shaft 74 and is connected to the tube 25 by a crank arm 78 and a pin 77 having a substantially spherical end 76. As is best shown in FIGS. 1, 6 and 7, the shaft 74 is fixed in a bore 79 of a drive member 80 by means of a pair of set screws 81. The drive member 80 is generally cylindrical with a bore 79 and a bore 84. Bore 84 is offset from but parallel to the central longitudinal axis of the member 80. A driven sleeve member 83 fits into bore 84 of part 80. Sleeve member 83 is provided with a bore 85 which is parallel with bore 84 but offset therefrom by the same distance as is the bore 84 from bore 79.

A bearing sleeve 86 is press fitted into the bore 85 and slidably receives the ball 76 on the end of the connecting pin 77. It may thus be seen that with the sleeve 83 angularly positioned relative to the driving member 80 such that the bore 85 is angularly displaced relative to the driving shaft 74, as the shaft 74 rotates the bore 85 travels in a circular orbit. The diameter of the orbit is zero when the bores 79 and 85 are in mutual alignment, as shown in FIG. 1, and is at a maximum when the .bores are at the maximum mutual displacement. For convenience of use, a reference mark 87 is provided on the member 80 and a plurality of index marks forming a scale 88 are provided on the sleeve 83 adjacent thereto. A lock screw 89 is provided for locking the members 80 and 83 in the adjusted position. The member 80 is provided with an annular groove for receiving the end of the screw 89 to maintain the orbit adjusted in the assembled condition.

In order to cause the end of the drill to travel in an elliptical orbit thereby to provide a groove 17 which is wider and thus preferable to an arcuate groove would be provided if the orbit were circular, the axis of the shaft 74 is disposed at a substantial angle relative to the axis of the tube 25. In the illustrated embodiment of the invention the shaft 74 and the tube 25 are disposed one above the other and their axes intersect at an angle of about 20.

The grinding wheel 12 is mounted'directly on the shaft of an electric motor 90 mounted on a yoke frame 91 which is pivotally mounted to a swivel frame 92 by a rod 93. The swivel frame 92 includes a base plate 94 which rests on a thrust bearing 95 (FIG. 8) for rotation about a mounting post 96. The post 96 is threaded at the top to receive a jam nut 97 and is transversely bored near the bottom to receive a locking shaft 98 having a lever handle 99 fastened thereon. The shaft 98 has an eccentric portion 100 positioned in the transverse bore in the post 96 so that in one position of the shaft 98 (as shown in FIG. 8) the swivel frame 92 can be rotated on the bearing 95. With the shaft 98 turned through about 30, the post is pulled down to lock the swivel frame 92 against rotation.

The swivel frame 92 has an upper arm 104 provided near its distal end with a bore for slidably receiving a lead screw 105 on the upper end of which is mounted the handwheel 16. The lead screw 105 is threaded through a cross rod 106 which is slidably received in a slot 107 in an upstanding arm portion 108 of the yoke frame 91. Rotation of the screw 105 by the handwheel 16 thus causes the yoke 91 to pivot in the swivel frame 91 to move the grinding wheel toward or away from the drill 15. A graduated ring 113 is mounted to the screw 105 above the frame arm 104 to facilitate grinding of equal depth grooves 17 in opposite sides of the web.

The angular position of the swivel frame determines the angle which the plane of the grinding wheel 12 makes with the axis of the drill 15. Generally this angle should be about 25, and a bracket 109 having an adjustable stop member 110 threaded therein is welded to the frame 20 to so position the grinding wheel. When mounting a drill in the assembly 13, the lever 99 may be turned to release the swivel frame which may then, by means of a knob 111 at the top be pivoted rearwardly to move the grinding wheel 12 out of the way.

OPERATION In order to thin the web of a drill using the web thinning machine 10, the tube 26 is positioned relative to the tube 25 so that the point of the drill in question is to the left of the clamp posts 60 and 61 with the spring 29 fully extended. Because of the substantial variation in the lengths of drills as they are used and sharpened, the telescoping support enables the use of the machine for thinning the webs of all drills generally found in normal machine stops. With the tubes 25 and 26 thus adjusted, the drill is moved to the left and the handwheel 46 is rotated to bring the posts 60 and 61 into clamping engagement with the leading and trailing edges of the pointed ends of the flutes. With the grinding wheel 12 in an elevated position as shown in FIG. 1, the swivel frame is then swung forward against the stop 110 and the lever 99 is given a halfturn to lock the grinding wheel in place above the end of the drill. As noted hereinbefore, the wheel 12 will be automatically positioned above the web between the flutes at an angle of about twenty-five degrees. The wheel 12 preferably has a thickness no greater than about one-eigth inch so as not to grind the outer edges of the flutes. The motor 90 is then energized to rotate the grinding wheel 12 and the motor 73 is energized to cause the drill to orbit. The handwheel 16 is then rotated to lower the grinding wheel 12 until it is engaged by the web of the orbiting drill point. The wheel 16 is slowly turned until the desired cut has been made in the web. The reading on the ring 113 is noted and the wheel 16 is backed off to elevate the grinding wheel away from the drill. The motors are then de-energized, the grinding wheel moved out of the way. and the drill 15 is pushed into the tube out of engagement with the clamp posts 60 and 63, rotated through 180 and then permitted to move back against the posts under the force of the spring 29. The motors are again energized and the handwheel 16 is operated to slowly move the grinding wheel 12 into grinding engagement with the upper side of the drill web. When the reading on the ring 113 is the same as it was upon .completion of the first operation, the second groove The eccentric drive mechanism 14 as shown in the 6 drawings causes the tip of the drill to travel in a completely elliptical path thereby to contact the grinding wheel 12 during a portion of the total orbit. If desired,

however, the drive 14 may be modified such that the drill is oscillated back and forth only through the grinding portion of the orbit without any substantial change in the geometry of the groove ground in the web of the drill.

While the present invention has been described in connection with a particular embodiment thereof, it will be understood that those skilled in the art may make many changes and modifications without departing from the true spirit and scope thereof. Accordingly, the appended claims are intended to cover all such changes and modifications as fall within the true spirit and scope of the present invention.

What is claimed is:

1. Web thinning apparatus, comprising first means for mounting a drill and securing it against rotation on its own axis,

second means for removing metal from said drill upon contact therewith; and

third means for moving one of said first and second means with respect to the other along an elliptical path at a location where said drill intercepts said second means,

whereby said second means removes a portion of the material from a drill held by said first means by sweeping across a portion of its web.

2. Web thinning apparatus according to claim 1 wherein said first means comprises an elongated tubular member for receiving the shank end of said drill,

means mounting said tubular member for universal movement about a point on the principal axis thereof, and

said third means comprises an eccentric drive connected to said tubular member at a location axially displaced from said point.

3. Web thinning apparatus according to claim 2 further comprising clamp means mounted to one end of said tubular member for engaging said drill near the point thereof.

4. Web thinning apparatus according to claim 3 wherein said clamp means comprises a pair of drill engaging members each adjustably movable in an arcuate path toward and away from said drill.

5. Web thinning apparatus according to claim 4 comprising spring means mounted in said tubular member for biasing said drill toward said drill engaging members.

6. Web thinning apparatus according to claim 1 wherein said second means is a grinding wheel, and further comprising a motor drivingly connected to said wheel,

a support for said motor, and

means mounting said support for movement of said grinding wheel in a fixed plane toward and away from said drill.

7. Web thinning apparatus according to claim 6 comprising a lead screw for controllably moving said support.

8. Web thinning apparatus, comprising first means for mounting a drill and securing it against rotation on its own axis,

second means for removing metal from said drill upon contact therewith; and

third means for moving said first and second means with respect to each other along an intercepting path including an elliptical segment at a location where said drill intercepts said second means,

said third means including,

means mounting said drill for universal movement about a point on the axis thereof,

an output shaft disposed in a plane of said axis and extending at an angle relative to said axis,

a pin,

a crank arm connected between said pin and said first means, and

an orbit adjustor interconnected between said output shaft and said pin to permit adjustment of the size 8 of said orbit. 9. Web thinning apparatus according to claim 8 wherein said orbit adjustor comprises justable, fixed relative position. 

1. Web thinning apparatus, comprising first means for mounting a drill and securing it against rotation on its own axis, second means for removing metal from said drill upon contact therewith; and third means for moving one of said first and second means with respect to the other along an elliptical path at a location where said drill intercepts said second means, whereby said second means removes a portion of the material from a drill held by said first means by sweeping across a portion of its web.
 2. Web thinning apparatus according to claim 1 wherein said first means comprises an elongated tubular member for receiving the shank end of said drill, means mounting said tubular member for universal movement about a point on the principal axis thereof, and said third means comprises an eccentric drive connected to said tubular member at a location axially displaced from said point.
 3. Web thinning apparatus according to claim 2 further comprising clamp means mounted to one end of said tubular member for engaging said drill near the point thereof.
 4. Web thinning apparatus according to claim 3 wherein said clamp means comprises a pair of drill engaging members each adjustably movable in an arcuate path toward and away from said drill.
 5. Web thinning apparatus according to claim 4 comprising spring means mounted in said tubular member for biasing said drill toward said drill engaging members.
 6. Web thinning apparatus accordIng to claim 1 wherein said second means is a grinding wheel, and further comprising a motor drivingly connected to said wheel, a support for said motor, and means mounting said support for movement of said grinding wheel in a fixed plane toward and away from said drill.
 7. Web thinning apparatus according to claim 6 comprising a lead screw for controllably moving said support.
 8. Web thinning apparatus, comprising first means for mounting a drill and securing it against rotation on its own axis, second means for removing metal from said drill upon contact therewith; and third means for moving said first and second means with respect to each other along an intercepting path including an elliptical segment at a location where said drill intercepts said second means, said third means including, means mounting said drill for universal movement about a point on the axis thereof, an output shaft disposed in a plane of said axis and extending at an angle relative to said axis, a pin, a crank arm connected between said pin and said first means, and an orbit adjustor interconnected between said output shaft and said pin to permit adjustment of the size of said orbit.
 9. Web thinning apparatus according to claim 8 wherein said orbit adjustor comprises a drive member, a driven member, said drive and driven members being connected together for mutual rotation and being respectively connected to said output shaft and to said pin at locations offset from the axis of mutual rotation of said drive and driven members, and means for securing said members together in an adjustable, fixed relative position. 